Modifying polymers



United States Patent 3,284,421 MODIFYING POLYMERS David S. Breslow, Wilmington, Del., assignor to Hercules Incorporated, a corporation of Delaware No Drawing. Filed June 20, 1963, Ser. No. 289,427 The portion of the term of the patent subsequent to Oct. 12, 1982, has been disclaimed 20 Claims. (Cl. 260-805) This application is a continuation-in-part of my copending applications Serial No. 172,815, filed February 12, 1962, now Patent No. 3,211,752, and Serial No. 247,878, filed December 28, 1962, now abandoned.

This invention relates to modifying polymers and to the products so produced. More particularly, the invention relates to modifying polymers with azidoformate compounds and the products so produced.

In the past, industry has depended almost entirely upon sulfur or sulfur-bearing materials as vulcanizing, i.e., cross-linking, agents. It has more recently been discovered that certain types of organic peroxides or azo compounds are capable of acting as vulcanizing agents. However, all of the above agents suffer the drawback that because of their mode of action they are not equally effective in cross-linking all types of polymers. For example, polybutadiene is effectively vulcanized by peroxides while butyl rubber or crystalline polypropylene are not.

Now in accordance with this invention it has unexpectedly been found that a number of polymers can be cross-linked by nonvolatile azidoformate compounds to produce vulcanizates that are tough, resilient, solvent resistant, and odor free. In addition, it has been found that the polymers can be treated with smaller amounts of the azidoformates to improve their properties without materially aifecting their solubility.

The azidoformates used in accordance with this invention are solids or oils having a boiling point of at least about 100 C. at a pressure of 70 mm. of mercury and having the general formula where x is at least 1, preferably from about 1 to about 100, and R is an organic radical, inert to modification reactions, containing at least one carbon atom per azidoformate group. Exemplary of the azidoformates used are the alkyl azidoformates such as n-octadecyl azidoformate, tetramethylene-bis(azidoformate), pentamethylene-bis (azidoformate); the cyclic alkyl azidoformates such as 1,4-cyclohexanedimethyl-bis (azidoformate), 2-(1- p-methyl-8-yloxy)ethyl azidoformate; 2 norborn--enyl methylene azidoformate; the aralkyl azidoformates such as a,oi-p-xylylene-bis(azidoformate); the aromatic azidoformates such as phenyl azidoformate, 2,2-isopropylidenebis(p,p'-phenyl azidoformate); the azidoformate ethers such as 2,2'-oxydiethyl-bis(azidoformate), 2,2-0xydipropyl-bis (azi-doformate 2,2'-ethylenedioxydietihyl-bis azidoformate), the tetraazidoforrnate of pentaerylthritolpropylene oxide adduct having the general formula the azidoformate thioethers such as 2,2'-thiodiethyl-bis (azidoformate), 4,4 -thiodibutyl-bis(azidoforrnate); etc. It will, of course, be obvious to those skilled in the art that still other azidoformates containing functional groups, which are inert to modification reactions, such as halogen, COOR,

3,284,421 Patented Nov. 8, 1966 etc., groups, are included in the above definition. In addition to their ability to cross-link, the azidoformates can be synthesized so as to contain groups which will affect other changes in the polymers treated. Thus it is possible by means of this invention to bond, directly to the polymers, dyes, stabilizers, flameproofing agents, antistatic agents, ultraviolet screening agents, etc. This can be done by using a compound which has been synthesized to contain both a color, stability, etc., causing group and at least one azidoformate group. Exemplary of such compounds are 3-hydroxy-4-benzoylphenyl azidoformate (an ultraviolet screening agent), p-phenylazophenyl azidoformate (a dye), 3,5-di-tert-butyl-4-hydroxybenzyl azidoformate (an antioxidant), the phosphate ester of phydroxyphenyl azidoformate (a flame-proofing agent), etc.

The azidoformates used in this invention can be prepared in various ways as, for example, by reacting a chloroformate with an excess, i.e., from about 1.05 moles to about 10 moles per equivalent of chloroformate, of an alkali azide. The preparation of the azidoformates is further described in my copending application Serial No. 172,815, filed February 12, 1962.

Any types of hydrocarbon poymer, including saturated, unsaturated, linear atactic, crystalline, or nonlinear amorphous polymers, copolymers, terpolymers, etc., as, for example, polyethylene, polypropylene, polystyrene, styrenebutadiene rubber, butyl rubber, natural rubber, polybutadiene, polyisobutylene, ethylene-propylene copolymer, cis-l,4-polyisoprene, ethylene-propylene-dicyclopentadiene terpolymer, etc., and blends of these polymers with each other or nonhydrocarbon polymers can be modified with any azidoformate provided it has a boiling point of at least about C. at a pressure of 70 mm. of mercury. In addition to the hydrocarbon polymers, a large number of nonhydrocarbon polymers including copolymers, terpolymers, etc., can also be modified with the new azidoformates. Typical of these nonhydrocarbon polymers are the cellulose esters such as cellulose acetate butyrate; the cellulose partial alkyl ethers such as hydroxyethyl and hydroxypropyl cellulose; polyesters such as poly(ethylene terephthalate), drying and nondrying alkyd resins, etc.; the poly(alkylene oxides) such as poly(ethylene oxide) and poly(propylene oxide); the polyamides such as nylon, Perlon-L, etc.; allyl pentaerythritol derivatives such as the condensate of triallyl pentaerythritol with di-allylidene pentaerythritol, esters of triallyl pentaerythritol and drying oil fatty acids, etc.; the poly(vinyl alkyl ethers) such as poly(vinyl methyl ether), etc.; the poly(vinyl acetals) such as poly(vinyl butyral), etc.; the vinyl chloride polymers containing at least 10 mole percent of vinyl chloride such as poly(vinyl chloride), vinyl chloride-vinyl acetate copolymers, vinyl chloride-vinylidene chloride copolymers, vinyl chloridemaleic anhydride copolymers, vinyl chloride-fumaric acid copolymers, vinyl chloride-vinyl acetal copolymers such as the vinyl chloride-vinyl butyral copolymers, vinyl chloride-vinylidene chloride-acrylonitrile terpolymers, vinyl chloride-vinyl acetate-maleic anhydride terpolymers, etc.; nitrocellulose; chlorinated natural rubber; sulfochlorinated polyethylene; polysulfide rubber; polyurethane rubber; poly(vinyl acetate); ethylene-vinyl acetate copolyrners; poly(vinylidene chloride); vinylidene chloride-ac rylonitrile copolymers; ethyl acrylate-Z-chloroethyl vinyl ether copolymers; poly(ethyl acrylate); poly(ethyl methacrylate; poly[3,3 bis(chloroniethyl)oxetane]; vinyl modified polydimethyl siloxane; polychloroprene; butadiene-acrylonitrile copolymers; etc.

The modification process can be carried out by either heating the polymer plus the azidoforrnate compound above its decomposition temperature or by exposing the polymer plus the azidoformate to irradiation. The temperature at which cross-linking or other modification is effected can be varied over a wide range. When it is effected by heating, the temperature will be in the range the uncross-linked polymer was soluble and for the degree of swell therein, hereinafter termed percent gel and percent swell. Percent gel is indicative of the percentage of polymer that is cross-linked and percent of from'a'bout 70 C. to about 350 C. Cross-linking 5 swell is inversely proportional to the cross-link density. or other modification effected by irradiation is independ- Percent gel and swell are determined as follows: A ent of temperature and can be performed at or below Weighed sample of cross-linked polymer is soaked in room temperature. The rate of the reaction depends a solvent, in which, the uncross-linked polymer was solon the intensity of the light source and the distance uble, at an elevated temperature for a specified length of the polymer therefrom. The wave lengths used will of time. The sample is then removed, blotted on filter generally be in the range of from 1 A. to about 5800 A. paper so as to remove the solvent on the surface and and most preferably from about 2000 A. to about 3000 weighed at once. The swollen sample is then dried to A. These can be supplied by sources such as high and constant weight. The weights of initial and final sample low pressure mercury lamps, cathode ray tubes, etc. are corrected for polymer and copolymer content based Photosensitizers can be added to increase the absorpon knowledge of components. From these figures tion. Various amounts of azidoformate can be added, the optimum amount depending on the amount of cross- WX100=percent gel linking or other modification desired the specific azido- Orrec 6 m1 1a Welg t 3 formate compound employed, etc. For example, in some Corrected Swollen weight*corrected y cases such as in certain film applications, it may be Corrected dry weight Elesirable to meretliy add a sulfficierllt amlount of aziciopercent n ormate compoun to strengt en t e po ymer or po ymer blend without materially affecting its solubility. In g: f ziggggg ig 35255 ,2; z ggi ig croisgeneral, the amount added, based on the weight of the b d d g polymer, will be from about 0.01% to about 20%. In i 5; $1 y h g some cases, it may be desirable to add a small amount, i uce 8 1 c p t: i.e., from about 0.01% to about 1.0% of sulfur which g I 0 uhlon 0 t 6 p0 ymer seems to act as a co-agent for the azidoformates. per m 0 so utlon) 0 t e polymer at elevated tem- The azidoformate can be incorporated in the polymer in any desired fashion; for example, it can be uniformly 3O EXAMPLES 1 10 blended by simply milling on a conventional rubber mill Ten samples of elastomeric ethylene-propylene copolyor dissolved in a solution containing the polymer. By mers were cross-linked with different azidoformates as either means it is distributed throughout the polymer follows: In each example the copolymer and azidoforand uniform cross-linking or other modification is effected mate were codissolved in carbon tetrachloride and then when the blend is either subjected to heat or irradiation. the solvent was allowed to evaporate overnight at room Other means of mixing the azidoformate with the polytemperature. Each mixture was cured by heating in a mer will be apparent to those skilled in the art. closed iron mold for one hour at a temperature of 160 In addition to the azidoformate, other ingredients can C. The resulting vulcanizates were odorless and had also be incorporated. The additives commonly used in not disclosed. The specific azidoformate used, the rubber vulcanizates can be used here also, as, for examount of each azidoformate used, the mole percent ample, extenders, fillers, pigments, plasticizers, stabilizers, of propylene and RSV of the ethylene-propylene copolyetc. When modification is effected by irradiation, addimer and the percent gel of the resulting vulcanizate, as tives should be used in amounts which do not inhibit determined in toluene at C., are tabulated in Table I.

Table I Mole Percent Parts/100 Percent Example Propylene RSV* Azidoformate Parts of Gel Copolymer 29 4 .0 Tetramethylene-bis (azidolromate) 7 29 4 .0 2, 2-oxydiethyl-bis(azidoformate) 5 87 29 4 .0 2, 2-ethylenedioxydiethyl-bis(azidortormate) 5 81 31 1. 9 2, 2'-oXydipropyl-bis(azidoformate) 5 83 31 1.9 2, 2-thiodiethyl-bis(azidoformate) s 76 31 1 .9 Pentamethylene-bis(azidoformate) 10 88 31 1.9 n-Oetadecyl azidoformate 17 76 31 1 .9 a, a-p-Xylylene-bis(azidoformate) 5 90 9 31 1.9 C(CH:OCHgCHOCN 5 66 10 31 1.9 2, 2-ti)0pr0pylidene-bis(p, p-pheny1 azidoform- 5 89 *As determined in decahydronaphthalene at a temperature of 135 C.

sis for percent gain in insolubility in solvents in which 75 by EXAMPLES 11-20 Ten samples of different elastomerie polymers were cross-linked with tetramethylene-bis(azidoformate) The formulation of each sample was as follows:

Parts Elastomeric polymer High abrasion furnace black 50 Tetramethylene-bis(azidoformate) 5.0

Each formulation was compounded on a two roll mill conventional rubber procedure and then cured in a a pressure of 800 p.s.i.

The resulting vulcanizates were odorless. The specific polymers cross-linked, the amounts of azido'formate cross-linking agent used, the time and temperature of the curing cycle, the percent gel and con- Table II Tensile Modulus Examples Elastomeric Polymer Strength, at 100% Elongation, Shore A p.s.i. Elongation, Percent Hardness 11 Polyethylene (density 0.923, melt index 2.1, 2, 765 2, 385 135 96 ASTM D1238 12 Natural rubber (smoked sheet) 3, 595 415 320 66 13 is-1,4-polyisoprene (containing 92.6% of the cis 2,800 430 300 67 monomer). l4 Styrene-butadiene copolymer (containing 23.5% of 2, 925 430 275 68 bound styrene 15 Isobutylene-isoprene copolymer (containing 2.25 1,275 210 370 47 mole oi isoprene). 16 Cis-1,4.-polybutadiene (containing 91% of the cis 1, 440 520 140 73 monomer). 17 Butadiene-acrylonitrile copolymer (containing 26 2,985 750 205 69 mole of acrylonitrile). 18 Vinyl modified polydimethyl-siloxaue 500 175 215 45 19. Polyohloroprene (sulfur free) 3, 455 1, 510 170 79 20. Suliochlorinated polyethylene (containing 29% by 2, 015 1, 080 165 72 weight of chlorine, and 1.25% by weight of sulfur, density 1.10).

EXAMPLES 2128 ditrons under WhlCh the percent gel was determined are Eight samples of dliferent polymers were cross-linked Set forth In Table Table 111 Parts of cross- Curing Curing Examples Polymer linking agent/ temperatime, Percent Conditions for gel determination 100 parts of ture, 0. minutes gel polymer 21 Poly(vinly chloride) (Sp. Viscosity 0.55, 170 84.0 thours at 50 0. inmethylethyl determined on a 4% solution in nitroketone. benzene at 0.). 22 Polyethylene (density 0.942, melt index 0.6, 2 170 10 95.7 16 hours at 140 0. in decahydro- ASTM D123 naphthalene. 23 Polyethylene (density 0.962, melt index 0.8, 2 170 10 96 .0 16 hours at 140 0. in decahydro- ASTM D1238). naphthalene. 24 Polypropylene (density 0.905, birefringent 2 195 5 99 .0 16 hours at 140 0. in decahydro- M.P. 167 0. naphthalene. 25 Polymeric 3,3-bis(chloromethyl)oxetane (bi- 5 210 5 91.0 16 hours at 100 0. in cyclohexrefringent M.P. 186.7 0.). anone. 26 Poly(ethylene oxide) (RSV 6.3 as deter- 5 150 75 .5 4 hours at 0. in water.

mined in chloroform at 25 0.). 27 Chlorinated natural rubber (67% by weight 5 135 88.0 4 hours at 25 C. in a mixture of 2 chlorine, viscosity cp. as determined parts benzene and 1 part non a. 20% solution in toluene at 25 0.). hexane. 28 Hydroxyeithyl cellulose (degree of substitu- 5 30 64.2 4 hours at 60 0. in water.

tion 2.5

with tetramethylene-lbis(.azidoforrnate). the form of flakes was slurried in acetone at a concentration of 1 gram of polymer per ml. of acetone. To each slurry was added the desired amount of azidoformate cross-linking agent dissolved in'chloroform. Each mixture was agitated and then the acetone and chlorofor-m removed by evaporation at a temperature of between 50 and 70 C. The resulting dry mixtures were further mixed and blended to thoroughly distribute the Each sample in 50 EXAMPLES 29-33 Five samples of difierent polymers were cross-linked with tetramethylene-bis(azidoformate). Each polymer was dissolved in an organic solvent and the desired amount of tetramethylene-bis(azidoformate) dissolved in chloroform was added with agitation. The specific polymers, their organic solvents and the amounts of azidoformate cross-linking agent added are tabulated below:

Parts of cross-linking Example Polymer Organic solvent agent/100 parts of polymer 29 Poly(viny1 acetate) (viscosity 900 cp. as de- Methanol 5 gggnined on a molar solution in benzene at 30 Polystyrene (mol. wt. 300,000) Benzene 2 31 Poly (ethyl aerylate) (RSV 1.86 as determined Methylethyl ketone 2 in ethylene dichloride at 25 0.). 32 Cellulose acetate butyrate (containing 13% Acetone 5 acetyl and 37% butyryl) 33 Poly (vinyl methyl ether) (RSV 13.9 as de- Benzene 2 crystalline) termined in chloroform at 25 0 azidoformate through the polymers. Each mixture was The above solutions were agitated automatically for 16 cured in an aluminum mold at elevated temperature under 75 hours and then the solvents were removed by evaporation at a temperature of between 50 and 70 C. Each 4 Parts sample was cured in an aluminum mold at e evated t rn- N t l bb oked heet) 50 perature under a pressure of 800' p.s.i. The resulting Ethy1ene propy1ene copolymer 5O vulcanizates were odorless. The specific polymers cross- Hioh abrasion furnace black 51 linked, the time and temperature of the curing cycle, the percent gel and conditions under which the precent gel Tetramethylene'bls(azldoformate) was determined are set forth in Table IV. Sulfur 0.175

Table IV Examples Polymers Curing tem- Curing time, Percent gel Conditions [or gel determination perature, 0. minutes Ioly(vinyl acetate) 170 97. 5 4 11101111153119 60 C. in ethylene di- 0 on e. Polystyrene 150 05. 0 16 hours at 25 C. in benzene. Poly(ethyl acrylate) 170 10 87.6 4l11{o1t1rs at 60 C. in methylethyl e one. Cellulose acetate butyrate 150 25 85.0 4 hours at 25 C. in acetone. Poly(vinyl methyl ether) 182 12 99. 0 7 hours at 66 C. in benzene.

EXAMPLE 34 A sample of an ethylene-propylene-dicyclopenta'diene terpolymer, containing 64.3 mole percent of ethylene, 33.3 mole mrcent of propylene and 2.4 mole percent of dicyclopentadiene and having an RSV of 1.9, as determined in decahydronaphthalene at a temperature of 135 C., was cross-linked with 2 parts per hundred of tetramethylene-bis(azidoformate). The azidoformate was incorporated in the terpolymer as described in Examples 1-10 and then the mixture was cured in a closed iron mold at 143 C. for 45 minutes. The resulting vulcanizate was odorless and had not discolored. It had a percent gel of 90 as determined in toluene at a temperature of 80 C.

EMMPLES 35 AND 36 Two samples of a polyisobutylene having a molecular weight of 100,000 were cross-linked with tetramethylenebis(azidoformate). The formulation of each sample was Each formulation was compounded on a two roll mill at a temperature of 27 C. for 25 minutes and then cured at 155 C. for 45 minutes in a closed iron mold. The resulting vulcanizates were odorless. The gel and swell percentages were determined in toluene at a temperature of 80 C. and are tabulated below:

Examples Percent gel 100 100 Percent swell- 355 237 EXAMPLE 37 A blend of natural rubber and an ethylene-propylene copolymer containing mole percent propylene and having an RSV of 2.3, as determined in decahydronaphthalene at a temperature of 135 C., were covulcanized. The following ingredients were compounded on a two roll mill at a temperature of from 70-75 C. for 20 minutes.

The resulting mixture were cured in a closed iron mold at a temperature of 155 C. for 30 minutes. The resulting vulcanizate was odorless. The properties of the vulcanizate were as follows:

Tensile strength, p.s.i 2880 Modulus at 300% elongation, p.s.i 1725 Elongation, percent 400 Shore A hardness 66 Break set, percent 10 EXAMPLES 38 AND 39 Two samples of an ethylene-propylene copolymer, containing 40 mole percent propylene and having an RSV of 2.3, as determined in decahydronaphthalene at a temperature of 135 C., were cross-linked with tetramethylene- The ingredients were compounded on a two roll mill at a temperature of 38 C. for 30 minutes and then cured in a preheated mold at a temperature of 155 C. for 45 minutes. The resulting vulcanizates were odorless. The tensile strength of each vulcanizate is tabulated below:

Examples Tensile strength, p.s.i 2, 895 3, 320

EXAMPLE 40 A sample of an ethylene-propylene copolymer, containing 32 mole percent propylene and having an RSV of 2.1 as determined in decahydronaphthalene at a temperature of 135 C., was cross-linked with 5 parts per hundred of 2-(1-p-menthyl-8-yloxy)ethyl azidoformate. The copolymer and azidoformatc cross-linking agent were compounded on a two roll mill at a temperature of from 60- C. The resulting mixture was cured in a preheated compression type mold at a temperature of 150 C, for 45 minutes. The resulting vulcanizate had a pleasant pine odor and had not discolored. It had a percent gel of 79 as determined in toluene at a temperature of 80 C.

9 EXAMPLE 41 A sample of an ethylenepropylene copolymer, containing 30 mole percent propylene and having an RSV of 2.1, as determined in decahydronaphthalene at a temper- 19 EXAMPLE 46 A sample of the poly(ethylene oxide) described in Example 26 was treated with 2 parts per hundred of tetramethylene bis(azidoformate). The azidoformate ature of 135 C., was cross-linked with 1,4-cyclohexanedi- 5 was incorporated in the polymer and the mixture cured methyl-bis(azidoformate). The following ingredients as described in Example 26. A control sample of the were compounded on a two roll mill at a temperature of poly(ethylene oxide) was cured in the same way except 38 C. for 30 minutes. no azidoformate was added. The two samples thus cured Ingredients: Parts were examined for strength and solubility. Both sam- Ethylene propylene copolymer M 100 ples were clear films of approximately 5 mils thickness. High abrasion furnace black 50 The untreated sample had a tendency to be brittle and 1,4-cyclohexanedimethyl-bis(azidoformate) 2 break q the treated samlile had a greater polymerized trimethyl dihydmquinoline (anti elongation capacity and was considerably stronger. oxidant) 05 Both samples dissolved in water at 50 C., the treated Sulfur 0.175 sample leaving only a slight residue of insoluble material. It can be seen from the above example that az1do- The resulting mixture were cured in a closed iron mold fo -mate cross-linking agents can be used to impart at a temperature of 150 C. for 30 minutes. The propstrength to films without materially affecting their solu erties of the vulcanizate were as follows: bility, thus demonstrating utility in the field of packaging Tensile strength, psi 2250 applications with water-soluble films.

Modulus at 300% elongation, p.s.i 1460 EXAMPLES 47-50 giggi fi gfigz 5 Four samples of dilferent coatingcompositions were Break Set percent 15 2f cross-linked with 2,2-1sopropy1 b1s(p,p'-phenylaz1doformate). The formulation of each sample is tabulated EXAMPLES 42-45 below.

Adhesive compositions were prepared from an atactic EXAMPLE 47 polypropylene having an RSV of 2.25 and an amorphous Ingredients: 1 Parts ethylene-propylene copolymer containing 33 mole percent Nltrocenulqse ""7 7 propylene and having an RSV of 22 In each case RSV Pentaerythritol-phthallc anhydnde-coconut 011 was determined in decahydronaphthalene at a temperatlkyd resm 21 ture of 135 C. The formulation of each example was Azldoformate 3 as follows: Toluene 32 35 Ethyl alcohol 1O Butyl acetate 15 Examples Ethyl acetate 15 Ingredients:

Parts Parts Parts Parts Glycerin-phthalic anhydride-soybean oil alkyd iliyiiiffiifi fiasrraaaras:3: if). "356 "n36 .resm I1- Heptaue 700 700 700 700 Mineral spirits 30 200 200 200 200 Azldoformate 10 Tetramethylene-bis(azldoformate). 10 10 EXAMPLE 49 Ingredients:

The dry ingredients were codissolved in the n-heptane Glycerin-phthalic anhydride-soybean oil-castor with agitation at room temperature. Each adhesive comil alkyd resin 65 position was tested by bonding compression molded X l 35 120-mil sheets of cgysalline IIpcillylpropylene (RSV 3.25 a; 0 A id f t 6,5 determined .in deca y ronap t a ene at a temperature 0 0 135 C.) as follows: From the crystalline polypropylene EXAMPLE 50 sheets were cut 1 by 2 inch specimens. Each specimen Ingredients. was swabbed with heptane and then coated with 50 mils D lailylldene .pentaerythntol'manyl pentaeryth' (wet) of adhesive composition. The coated specimens mol reaction "*1"? 100 were air dried at room temperature for 5 minutes, then Phlmyl ls'naphthylamme (antloxldant) 2 at a temperature of C. for 10 minutes and again at Azldoformate 10 room temperature for 30 minutes. Contact bonds were Each coating composition was spread on a glass plate, formed by overlapping two coated surfaces 1 square inch allowed to air dry at room temperature and then was under a pressure of 5 p.s.i. and a temperature of 133 C. baked at a temperature of C. for 1 hour. Four for two hours. The bonded specimens were conditioned 60 control samples were prepared and treated exactly the for one hour at room temperature (still under a pressure same way except the azidoformate was omitted from each of 5 p.s.i.) and then tested for lap shear bond strength formulation. The four coatings prepared with azidoand creep. The results of the tests are tabulated below: formate and the four control samples were all tested for Examples Lap shearbondstrength, p.s.i 390 60 20. Creep 2 weeks 3.5 min 2 weeksi... 3.0mm.

1 Measured by ASIM D1002 using an Instron tester at a loading rate of 20 inches per minute. 2 Measured by loading bonded specimens in tension with 500 grams dead weight at a temperature of 80 C. and

noting the time to bond failure.

3 Discontinued after 2 weeks with no visible evidence of bond failure.

1 1 cross-linking by determining their solubility in an excess of butyl acetate. The four coatings prepared with azidoformate were insoluble after soaking for 18 hours. The four controls rapidly dissolved in the butyl acetate.

EXAMPLE 1 Ingredients: Parts Styrene-butadiene copolymer 50 Ethylene-propylene copolymer 50 High abrasion furnace black 50 Polymerized trimethyl dihydroquinoline (antioxidant) 0.5 Sulfur 0.14 Tetramethylene-bis azidoformate) 1.5

The mixture was cured in a closed iron mold at a ternperature of 150 C. for 45 minutes. The resulting vulcanizate was odorless and exhibited the following properties:

Tensile strength, p.s.i 2360 Modulus at 300% elongation, p.s.i 1085 Elongation, percent 565 Shore A hardness 61 Break set, percent 25 EXAMPLE 5 2 A blend of 160 parts of a high density polyethylene having an RSV of 1.5 as determined in decahydronaphthalene at a temperature of 135 C. and 40 parts of a polysiobutylene having an average molecular weight of 100,000 was prepared by blending on a two roll mill at a temperature of 127 C. To the blend was added, dropwise over a period of 5 minutes, 2 parts of tetramethylene bis(azidoformate) dissolved in ethylene dichloride. A sample was removed from the mill, placed in a mold and cured for minutes at a temperature of 170 C. under a pressure of 800 p.s.i. The resulting vulcanizate had a percent gel of 93.7 and a percent swell of 630. The properties of the vulcanizate were as follows:

Tensile strength, p.s.i 2110 Youngs modulus, p.s.i 115,000 Elongation, percent 83 EXAMPLE 5 3 A sample of an ethylene-propylene copolymer having an RSV of 1.9, as determined in decahydronaphthalene at a temperature of 135 C. and containing 31 mole percent of propylene was cross-linked with tetramethylene bis (azidoformate). Quartz equipment was used throughout the reaction. The azidoformate was added to a solution of the copolymer in toluene in an amount of 10 parts per hundred parts of copolymer, and the solvent was allowed to evaporate overnight, at room temperature. The sample was then irradiated for 2 hours with a low pressure mercury vapor light (36 watt) at a distance of 3.75 inches. At least 90% of the radiation given off by the light was at 2537 A. The resulting vulcanizate had a percent gel of 84 as determined in toluene at a temperature of 80 C. A sample of the ethylene-propylene copolymer treated in exactly the same way except for the addition of azidoformate was completely soluble in toluene at 80 C.

EXAMPLE 54 methylene bis(azidoformate) exactly as described in Example 53. The resulting vulcanizate was substantially insoluble in toluene at a temperature of C. while a sample of the polymer treated in exactly the same way except for the addition of the azidoformate was completely soluble in toluene at 80 C.

EXAMPLES 55-57 Three samples of different polymers were cross-linked with tetramethylene bis(azidoformate). Each polymer was dissolved in a solvent, chloroform in the case of poly(vinyl methyl ether) and ethylene dichloride in the case of the other two polymers, and the azidoformate was added to each solution in an amount of 10 parts per hundred parts of polymer. Each sample was poured on a glass plate and the solvent allowed to evaporate. The resulting thin (about 0.5 mil) films were each irradiated for 15 minutes with a low pressure mercury vapor light (36 watt) at a distance of 1 inches. The polymers cross-linked and the percent gel of each, as determined in ethylene dichloride at a temperature of 25 C. are tabulated below.

Percent gel Poly(vinyl methyl ether) 91 Poly(ethylene oxide) 70 Hydroxypropyl cellulose EXAMPLES 58-60 Three samples of different elastomeric polymers were cross-linked with tetramethylene bis(azidoformate). The formulation of each sample was as follows:

Parts Elastomeric polymer High abrasion furnace black 50 Tetramethylene-bis(azidoformate) 3 Polymers Gel Swell Polysulfide 1 94 290 Polyurethane 2 91 330 Ethyl acrylate-Z-chloroethyl vinyl ether copolymer 87 374 1 An organic polysulfidc sold as 'lliiokol ST. 1 Reaction product of toluene diisocyanate and a polyalkylene ether glycol.

3 Containing approximately 95 mole percent; ethyl acrylate.

EXAMPLE 61 This example demonstrates the cross-linking of a polyamide fiber. A sample of a 6,6-nylon type polyamide fiber (840 denier; filaments; 2 ply) was immersed in a 14.5% solution of 2,2-isopropylidene bis(p,p'-phenyl azidoformate) in ethylene dichloride. In addition to the cross-linking agent, the solution contained a small amount of phenol which acted as a swelling agent for the fiber. The fiber was soaked in the solution for 16 hours at a temperature of 52 C., then removed and air-dried. The thus treated fiber was heated in a closed container for 30 minutes at a temperature of 149 C. The fiber was tested for cross-linking by determining its solubility in an excess of formic acid at a temperature of 80 C. The fiber was insoluble after soaking for 4 hours while a sample treated exactly the same way except for the azidoformate completely dissolved.

EXAMPLE 62 A sample of polyester fiber, sold under the trademark Dacron, type S 1100 denier; 250 filaments; 3 ply), was immersed in a 16.6% solution of tetramethylene bis (azidoformate) in ethylene dichloride. In addition to the cross-linking agent, the solution contained a small amount of phenol which acted as a swelling agent for the fiber. The fiber was soaked in the solution for 16 hours at a temperature of 52 C., then removed and air-dried. The thus treated fiber was heated in a closed container for 30 minutes at a temperature of 149 C. The fiber was tested for cross-linking by determining its solubility in an excess of p-cresol at a temperature of 145 C. The fiber was insoluble after soaking for 64 hours While a sample treated exactly the same way except for the azidoformate completely dissolved.

EXAMPLE 63 This example demonstrates the cross-linking and dyeing of an ethylene-propylene copolymer with a dye synthesized to contain an azidoformate group. To a toluene solution of an ethylene-propylene copolymer, containing 31 mole per cent propylene and having an RSV of 1.9, as determined in decahydronaphthalene at a temperature of 135 C., was added 17 parts per hundred parts of copolymer of p-phenylazophenyl azidoformate. The solvent was allowed to evaporate overnight at room temperature. The resulting bright orange rubbery material was heated in a closed iron mold for one hour at 130 C. The bright orange vulcanizate was tested for cross-linking and fastness of color by continuous extraction with an excess of tetrachloroethylene for 7 hours at room temperature. The vulcanizate was color fast and insoluble. A sample of the copolymer treated in the same Way except for the addition of p-phenylazophenyl azidoformate was white and completely dissolved in the tetra-chloroethylene.

EXAMPLES 64-66 Samples of three different polymer compositions were cross-linked with azidoformate exactly as described in Examples 4750. The formulation of each sample is tabulated below.

EXAMPLE 64 Ingredients Parts Vinyl chloride-Vinyl acetate copolymer 20 Butyl acetate 80 Tetramethylene bis(azidoformate) 20 EXAMPE 65 Ingredients Parts Poly(vinyl butyral) 20 Ethanol 80 2,2-isopropyl bis(p,p-phenylazidoformate) EXAMPLE 66 r Ingredients: Parts Vinylidene chloride-acrylonitrile copolymer 20 Methyl ethyl ketone 80 Tetramethylene bis(azidoformate) 10 Three control samples were prepared and treated exactly the same way except the azidoformate was omitted from each formulation. The compositions and controls were all tested for "cross linking by determining their solubility in an excess of the solvent in which they were applied, i.e., butyl acetate in Example 64, ethanol in Example 65, and methyl ethyl ketone in Example 66. In each example the control was soluble and the composition containing the azidoformate insoluble after soaking for 18 hours.

EXAMPLE 67 A blend of polyisobutylene and crystalline polypropylene containing by weight of polyisobutylene was modified as follows: The polyisobutylene and polypropylene were compounded on a two-roll mill until a uniform blend was obtained. Then an amount of 50% tetramethylene bis(azidoformate) dispersed in finely pulverized silica equivalent to 0.025% by weight of pure azidoformate, based on the blended polymers, was added to the mill and compounded for approximately 1 minute at a temperature of C. The resulting mixture was heated in a closed iron mold at a temperature of C. for 20 minutes under a pressure of 1,000 p.s.i. The thus modified blend was compared to a control blend treated in exactly the same way except for the addition of the azidoformate. Both the modified blend and the control were soluble in hot decahydronaphthalene, but the impact strength of the modified blend as measured at 10 C. was approximately 10 ft. lbs./sq. in. higher than the control.

What I claim and desire to protect by Letters Patent 1. The process of modifying a polymer selected from the group consisting of hydrocarbon polymers, cellulose esters, cellulose partial :alkyl ethers, condensation prod nets of a dibasic acid and a polyhydric alcohol, poly (:alkylene oxides), polyamides, esters of allyl pentaerythritol with a fat-tty acid, condensation products of triallyl pentaerythritol and diallylidene pentaerythritol, poly(vinyl alkyl ethers), poly (vinyl acetals), poly(vinyl chloride), vinyl chloride-vinyl acetate copolymers, vinyl chloride-vinylidene chloride copolymers, vinyl chloridelmaleic anhydride copolymers, vinyl chl oride-ifumaric acid copolymers, vinyl chloride-vinyl acetal copolymers, vinyl chloride-vinylidene chloride acrylonitrile terpolymers, vinyl chloride-vinyl acetate-maleie anhyclride terpolymers, nitrocellulose, chlorinated natural rubber, polysulfides, polyurethanes, poly (vinyl acetate), ethylene-vinyl acetate copolymers, poly(vinylidene chloride), vinylidene chloride acrylonitrile copolymers, ethyl acrylate2 chloroethyl vinyl ether copolymers, poly-(ethyl acrylate), poxly Qethyl methacrylate), poly[3,3 -bis(chloromethyl) oxetane], vinyl modified polydimethyl-siloxanes, polychloroprene, butadiene-acrylonitrile copolymers, and sulfochlorinated polyethylene which comprises irradiating said polymer in admixture with a small amount of an azidofonrnate having a boiling point of at least about 100 C. at a pressure of 70 min. of mercury and having the general formula if R(OON where x is an integer of from about 1 to about 4 and R is an organic radical inert to said polymer, at a wave length between about 1 A. and about 5800 A.

2. A polymer selected from the group consisting of hydrocarbon polymers, condensation products of a dibasic acid and a polyhydric alcohol, cellulose esters, cellulose partial alkyl ethers, polyesters, poly(alkylene oxides), polyamides, esters of allyl pentaerythritol with a fatty acid, condensation products of triallyl pentaerythritol and diallylidene pentaerythritol, poly(vinyl alkyl ethers), poly (vinyl acetals), poly(vinyl chloride), vinyl chloride-vinyl acetate copolymers, vinyl chloride-vinylidene chloride copolymers, vinyl chloride-maleic anhydr-ide copolymers, vinyl chlonideafumaric acid copolymers, vinyl chloride-vinyl acetal copolymers, vinyl chloride-vinylidene chlorideacrylonitrile terpoilymers, vinyl chloride-vinyl acetate-imaleic anhydride terpolymers, nitrocellulose, chlorinated natural rubber, polysulfides, polyurethanes, .poly(vinyl acetate), ethylene-vinyl acetate copolymers, ipoly(vinylidene chloride), vinylidene chlorideacrylonitrile copolymers, ethyl acrylate-Z chloroethyl vinyl ether copolymers, poly(ethyl :acrylate), poly(e-thyl methacrylate), poly[l3,3-bis (chloromethyl)oxetane], vinyl modified polydimethylsiloxanes, poly-chloroprene, bUtEIIdIBIE-flCI'YlOIIltI'llG copolymers, and sulfochlorinated polyethylene, modified by irradiating said polymer in admixture with an azidoformate having a boiling point of at least about 100 C. at a pressure 07f 70 mm. of mercury and having the general formula where x is an integer of from about 1 to about 4 and R is an *organic radical inert to said polymer, at a Wave length between about 1 A. and about 5800 A.

3. The process of modifying a polymer selected from the group consisting of hydrocarbon polymers, cellulose esters, cellulose partial alkyl ethers, condensation products of a dibasic acid and a polyhydric alcohol, poly (alkylene oxides), polyamides, esters of allyl pentaerythritol with a fatty acid, condensation products of triallyl pentaerythritol and diallylidene pentaerythritol, poly (vinyl alkyl ethers), poly(vinyl acetals), poly(vinyl chloride), vinyl chloride vinyl acetate copolymers, vinyl chloride-vinylidene chloride copolymers, vinyl chloridemaleic anhydride copolymers, vinyl chloride-fumaric acid copolymers, vinyl chloride-vinyl .acetal copolymers, vinyl chloride-vinylidene chloride-acrylonitrile terpol-ymers, vinyl chloride-vinyl acetate-maleic anhy-dride terpolymers, nitrocellulose, chlorinated natural rubber, polysulfides, polyurethanes, poly (vinyl acetate), ethylenevinyl acetate copolymers, poly(vinylidene chloride), vinylidene chloride-acrylonitrile copolymers, ethyl acrylate- Z-chlonoethyl vinyl ether copolymers, poly(ethyil acrylate), poly(ethyl methacrylate), poly[3,3 bis(chloromethyl)oxetane], vinyl modified polydimethylsiloxanes, polychloroprene, butadiene acrylonitrile copolymers, and sulfochlorinated polyethyene which comprises heating said polymer at 'an elevated temperature with a small amount Otf an azidoformate having a boiling point of at least about 100 C. at a pressure of 70 mm. of mercury and having the general formula R'(O( ]Na)x where x is an integer of from about 1 to about 4 and R is an organic radical inert to said polymer.

4. The process of claim 3 wherein the polymer is a hydrocarbon polymer.

5. The process of claim 4 wherein the hydrocarbon polymer is an ethylene-propylene copolymer.

6. The process of claim 4 wherein the hydrocarbon polymer is an ethylene-propylene-dicyclopentadiene terpolymer.

7. The process of claim 4 wherein the hydrocarbon polymer is polyethylene.

8. The process of claim 4 wherein the hydrocarbon polymer is a styrene-butadiene copolymer.

9. The process of claim 4 wherein the hydrocarbon polymer is polypropylene.

10. The process of claim 3 wherein the polymer is a blend of hydrocarbon polymers.

11. The process of claim 3 wherein the polymer is chlorinated natural rubber.

12. The process of claim 3 wherein the polymer is poly(vinyl chloride).

13. The process of claim 3 wherein the polymer is polychloroprene.

14. The process of claim 3 wherein the polymer is a poly(alkylene oxide).

15. The process of claim 3 wherein the azidofonmate is tetramethylene-bis(azidoformate).

16. The process of claim 3 wherein the azidoformate is 1,4-cyclohex-anedimethylbis(azidoformate).

17. The process of claim 3 wherein the azidoformatc is 2-( lp-menthyl-S-y-loxy) ethyl azidoformate.

18. The process of claim 3 wherein the azidorformate is a,a'-p-xylylene-bis(-azidoformate).

19. The process of claim 3 wherein the polymer is cross-linked by said modification.

20. A polymer selected from the group consisting of hydrocarbon polymers, cellulose esters, cellulose partial alkyl ethers, condensation products of a dibasic acid and a polyhydric alcohol, poly(alkylene oxides), polyamides, esters of allyl pentaerythritol with a fatty acid, condensation products or" tiriallyl pentaerythritol and diallylidene pentaerythritol, poly( vinyl alkyl others), poly (vinyl acetals), poly(vinyl chloride), vinyl chloride-vinyl acetate copolymers, vinyl chloride-vinylidene chloride copolymers, vinyl chloride-maleic anhydride copolymers, vinyl chloride-fumaric acid copolymers, vinyl chloridevinyl acetal copolymers, vinyl chloride-vinylidene chloride-acrylonitrile terpolymers, vinyl chloride-vinyl acetate-m aleic anhydride terpolymers, nitrocellulose, chlorinated natural rubber, polysulfides, polyurethanes, poly (vinyl acetate), ethylene-vinyl acetate copolymers, poly (vinylidene chloride), vinylidene chloride-acrylonitrile copolymers, ethyl acrylate-2-chloroethyl vinyl ether copolymers, poly(ethyl acryla-te), poly (ethyl methacrylate), poly[3,3-bis(chloromethyl)oxetane], vinyl modified polydimethylsiloxianes, polychloroprene, butadiene acrylonitrile copolymers, and sulfochlorinated polyethylene, chemically modified by treatment with an azidoformate having a boiling point of at least about 100 C. at a pressure of mm. of mercury and having the \general formula where x is an integer of from about 1 to about 4 and R is an organic radical inert to said polymer at an elevated temperature.

References Cited by the Examiner UNITED STATES PATENTS 2,115,275 4/1938 Moran et al 260349 2,764,599 9/1956 Clifford et al. 260349 3,135,771 6/1964 Renclcholf et al. 260349 3,137,745 6/1964 Johnstone 26498 OTHER REFERENCES Schwyzer et al.: Helvetica Chimica Acta, vol. 42, Dec. 1, 1959, pp. 2622-4.

Weygand et al.: Berichte der Deutschen Chemischen Gesellschaf vol. 95, Jan. 25, 1962, pp. 1-6.

JOSEPH L. SCHOFER, Primary Examiner.

SAMUEL H. BLECH, Examiner.

L. EDELMAN, Assistant Examiner. 

3. THE PROCESS OF MODIFYING A POLYMER SELECTED FROM THE GROUP CONSISTING OF HYDROCARBON POLYMERS, CELLULOSE ESTERS, CELLULOSE PARTIAL ALKYL ETHERS, CONDENSATION PRODUCTS OF A DIBASIC ACID AND A POLYHYDRIC ALCOHOL, POLY (ALKYLENE OXIDES), POLYAMIDES, ESTERS OF ALLYL PENTAERYTHRITOL WITH A FATTY ACID, CONDENSATION PRODUCTS OF TRIALLY PENTAERYTHRITOL AND DIALLYLIDENE PENTARYTHRITOL, POLY (VINYL ALKYL ETHERS), POLY(VINYL ACETALS), POLY(VINYL CHLORIDE), VINYLCHLORIDE-VINYL ACETATE COPOLYMERS, VINYL CHLORIDE-VINYLIDENE CHLORIDE COPOLYMERS, VINYL CHLORIDEMALEIC ANHYDRIDE COPOLYMERS, VINYL CHLORIDE-FUMARIC ACID COPOLYMERS VINYL CHLORIDE-VINYL ACETAL COPOLYMERS, VINYL CHLORIDE-VINYLIDENE CHLORIDE-ACRYLONITRILE TERPOLYMERS VINYL CHLORIDE-VINYL ACETATE-MALEIC ANHYDRIDE TERPOLMERS, NITROCELLULOSE, CHLORINATED NAUTRAL RUBBER, POLYSULFIEDS, POLYURETHANES, POLY(VINYLIDENE CHLORIDE), VIVINYL ACETATE COPOLYMERS, POLY(VINYLIDENE CHLORIDE), VI NYLIDENE CHLORIDE-ACRYLONITRILE COPOLYMERS, ETHYL ACRYLATE2-CHLORETHYL VINYL ETHER COPOLYMERS, POLY(ETHYL ACRYLATE), POLY(ETHYL METHACRYLATE), POLY 3,3 - BIS(CHLOROMETHYL)OXETANEL!, VINYL MODIFIED POLYDIMETHYSILOXANES, POLYCHLOROPRENE, BUTADIENE ACRYLONITRILE COPOLYMERS, AND SULFOCHLORINATED POLYETHYENE WHICH COMPRISES HEATING SAID POLYMER AT AN ELEVATED TEMPERATURE WITH A SMALL AMOUN OF AN AZIDOFORMATE HAVING A BOILING POINT OF AT LEAST ABOUT 100*C. AT A PRESSURE OF 70 MM. OF MERCURY AND HAVING THE GENERAL FORMULA R(-O-CO-N3)X WHERE X IS AN INTEGER OF FROM ABOUT 1 TO ABOUT 4 AND R IS AN ORGANIC RADICAL INERT TO SAID POLYMER. 